Japanese Unexamined Patent Appl. Pub. JP-A-H11-231825 teaches a driving device for driving a display device using a subfield driving method. The driving device taught in JP-A-H11-231825 sends the acquired video data to a 1-field delay 111 and to a brightness detector 110. The brightness detector 110 detects the average brightness level in one field, and the average brightness signal output from the brightness detector 110 is delayed one field period. The multiplier 112 and gray level adjustment unit 114 that process signals parallel to the brightness detector 110 must process the signals for the same field as the signals acquired from the brightness detector 110, and the 1-field delay 111 is therefore inserted before the multiplier 112.